9/7텝을 갖는 정수 웨이브릿 변환을 이용한 무손실 정지영상 압축

추형석,서영천,전희성,이태호,안종구,Chu Hyung Suk,Seo Young Cheon,Jun Hee Sung,Lee Tae Ho,An Chong Koo 한국융합신호처리학회 2000 융합신호처리학회 논문지 (JISPS) Vol.1 No.1

In this paper, We compare the Harr wavelet of the S+P transform with various integer coefficient filter banks and apply 9/7 ICFB to the wavelet transform. In addition, we propose a entropy-coding method that exploits the multiresolution structure and the feedback of the prediction error, and can efficiently compress the transformed image for progressive transmission. Simulation results are included to compare to the compression ratio using the S+P transform with different types of images.

웨이블렛 패킷 기반 쿼드트리 알고리즘을 이용한 디지털 워터마킹의 성능 분석

추형석,김한길,안종구,Chu, Hyung-Suk,Kim, Han-Kil,An, Chong-Koo 한국융합신호처리학회 2010 융합신호처리학회 논문지 (JISPS) Vol.11 No.4

본 논문에서는 웨이브렛 변환과 쿼드트리 알고리즘을 이용한 디지털 워터마킹 알고리즘을 제안하였다. 제안한 알고리즘은 웨이블렛 변환과 웨이블렛 패킷 변환을 이용하여 입력영상을 변환하고, 쿼드트리와 Cox 알고리즘을 이용하여 워터마크를 삽입하였다. 제안한 알고리즘의 성능 평가를 위한 시뮬레이션은 DWT 변환 레벨과 대역(HH, LH, HL)에 따른 워터마킹 효과와 AWPT 변환 레벨에 따른 워터마킹의 효과에 대하여 수행하였고, DWT를 이용한 결과와 AWPT를 이용한 결과를 비교하였다. 또한 최저주파수대역(LL)의 워터마킹의 효과에 대하여 알아보았다. 시뮬레이션 결과에서 6 레벨 DWT의 HH, HL, LH 대역에 동시에 워터마크를 삽입하였을 경우에 다른 경우들과 비교하여 가장 좋은 결과를 보였다. 3 레벨의 AWPT의 결과는 3레벨의 DWT 결과와 비교하여 향상된 상관도 값을 보였다. 또한 전체 워터마크 중 30~60%를 LL 대역에 삽입하였을 경우에 PSNR 성능은 1~2dB 정도 떨어지나 추출한 워터마크의 상관도 값은 향상된 결과를 보였다. In this paper, digital watermarking method using wavelet transform and quad-tree algorithm is proposed. The proposed algorithm transforms the input image by DWT(Discrete Wavelet Transform) and AWPT(Adaptive Wavelet Packet Transform), inserts the watermark by quad-tree algorithm and the Cox's algorithm. The simulation for performance analysis of the proposed algorithm is implemented about the effect of embedding watermark in each subband coefficient (HH, LH, HL) of DWT, each DWT level, and each AWPT level. The simulation result by using DWT is compared with that using AWPT in the proposed algorithm. In addition, the effect of embedding watermark in the lowest frequency band (LL) is simulated. As a simulation result using DWT, the watermarking performance of simultaneously embedding in HH, LH, and HL band of DWT(6 level) is better than that of different cases. The result of AWPT(3 level) improves the correlation value compared to that of DWT(3 level). In addition, insertion the watermark to the LL band about 30~60% of all watermarks improves the correlation value while PSNR performance decreases 1~2dB.

웨이블렛 패킷 변환을 이용한 디지털 워터마킹

秋亨錫(Hyung-Suk Chu),安鍾久(Chong-Koo An) 대한전기학회 2008 전기학회논문지 Vol.57 No.8

In this paper, a digital watermarking method using the WPT (Wavelet Packet Transform) is proposed. The proposed algorithm transforms the input image by using the WPT and inserts the watermark by using the quad-tree algorithm and Cox's algorithm. The experiments for evaluating the performances of the proposed algorithm is carried out by inserting a watermark in each wavelet packet transform step and by inserting a watermark into the lowest frequency domain (LL). As a simulation result, the performance of the insertion of the watermark into the 6 levels of WPT is better than that of other cases. In addition, about 30~60% of all watermarks are inserted into the LL band, the correlation value is improved though the PSNR performance decreases 1~2㏈.

에러 피드백의 컨텍스트 기반 예측기법을 이용한 무손실 영상 압축에 관한 연구

秋亨錫(Hyung-Suk Chu),朴柄秀(Byung-Su Park),安鍾久(Chong-Koo An) 대한전기학회 2007 전기학회논문지 Vol.56 No.12

In this paper, the wavelet transform based lossless image compression algorithm is proposed. The proposed algorithm transforms the input image using 9/7 ICFB and S+P filter, and eliminates the spacious correlation of the sub band coefficients, applying the context modeling predictive technique based on the multi-resolution structure and the feedback of the prediction error. The prediction context exploits the subordination and direction property of the different level subband in the vertical, horizontal, and diagonal subband coefficients. The simulation result of the high frequency images such as PEPPERS, BOAT, and AIRPLANE shows that the proposed algorithm efficiently predicts the edge area of each multi-resolution subband.

손실 압축을 위한 EZW 알고리즘의 개선에 관한 연구

秋亨錫(Hyung-Suk Chu),安鍾久(Chong-Koo Ahn) 대한전기학회 2007 전기학회논문지 Vol.56 No.2

Data compression is very important for the storage and transmission of informations. EZW image compression algorithm has been widely used in real application due to its high compression performance. In the EZW algorithm, when a new significant coefficient is generated, its children are all encoded, although its all descendants may be insignificant, and thus its performance is declined. In this paper, we proposed an improved EZW algorithm using IS(Isolated Significant) symbol, which checks all descendants of significant coefficient and avoids encoding the children of each newly generated significant coefficient if it has no significant descendant.

무손실ㆍ손실 영상 압축을 위한 웨이브릿 기반 알고리즘에 관한 연구

秋亨錫(Hyung-Suk Chu),安鍾久(Chong-Koo An) 대한전기학회 2006 전기학회논문지 D Vol.55 No.3

A wavelet-based image compression system allowing both lossless and lossy image compression is proposed in this paper. The proposed algorithm consists of the two stages. The first stage uses the wavelet packet transform and the quad-tree coding scheme for the lossy compression. In the second stage, the residue image taken between the original image and the lossy reconstruction image is coded for the lossless image compression by using the integer wavelet transform and the context based predictive technique with feedback error. The proposed wavelet-based algorithm, allowing an optional lossless reconstruction of a given image, transmits progressively image materials and chooses an appropriate wavelet filter in each stage. The lossy compression reslut of the proposed algorithm improves up to the maximum 1 ㏈ PSNR performance of the high frequency image, compared to that of JPEG-2000 algorithm and that of S+P algorithm. In addition, the lossless compression result of the proposed algorithm improves up to the maximum 0.39 compression rates of the high frequency image, compared to that of the existing algorithm.

웨이브릿 패킷 알고리즘을 이용한 3차원 비디오 서브밴드 코딩

秋亨錫(Hyung Suk Chu),安鍾久(Chong Koo An) 대한전기학회 2005 전기학회논문지 D Vol.54 No.11

사분트리 알고리즘과 기하학적 웨이블렛을 이용한 손실 영상 압축

추형석(Hyung-Suk Chu),안종구(Chong-Koo An) 대한전기학회 2009 전기학회논문지 Vol.58 No.11

In this paper, the lossy image compression algorithm using the quad tree and the bandlets is proposed. The proposed algorithm transforms input images by the discrete wavelet transform (DWT) and represents the geometrical structures of high frequency bands using the bandlets with a 8 block- size. In addition, the proposed algorithm searches the position information of the significant coefficients by using the quad tree algorithm and computes the magnitude and the sign information of the significant coefficients by using the Embedded Image Coding using Zerotrees of Wavelet Coefficients (EZW) algorithm. The compression result by using the quad tree algorithm improves the PSNR performance of high frequency images up to 1 dB, compared to that of JPEG-2000 algorithm and that of S+P algorithm. The PSNR performance by using DWT and bandlets improves up to 7.5dB, compared to that by using only DWT.

쿼드트리 알고리즘을 이용한 비디오 서브밴드 코딩

안종구,추형석,An, Chong-Koo,Chu, Hyung-Suk 한국융합신호처리학회 2005 융합신호처리학회 논문지 (JISPS) Vol.6 No.3

This paper presents the 3D wavelet based video compression system using quad-tree algorithm. The 3D wavelet based video compression system removes the temporal correlation of the input sequences using the motion compensation filter and decomposes the spatio-temporal subband using the spatial wavelet transform. The proposed system allocates the higher bit rate to the low frequency image of the 3D wavelet sequences and improves the 0.64dB PSNR performance of the reconstructed image in comparison with that of H.263. In addition to the limitation on the propagation of the motion compensation error by the 3D wavelet transform, the proposed system progressively transmits the input sequence according to the resolution and rate scalability. 본 논문에서는 3차원 웨이브릿 변환을 기반으로 하고 쿼드트리 코딩 알고리즘을 이용한 동영상 압축 시스템을 제안하였다. 3차원 웨이브릿 기반 비디오 압축 시스템은 3차원 웨이브릿 변환의 움직임 보상형 시간축 필터를 이용하여 입력영상신호의 시간적 상관관계를 제거하고, 공간상의 웨이브릿 변환에 의하여 시공간의 서브밴드로 분해한다. 제안한 시스템은 3차원 웨이브릿 영상에서 에너지가 집중된 저주파 영상에 상대적으로 비트율을 높게 할당하였고, H.263 알고리즘과 비교하여 복원된 영상의 PSNR 성능을 0.64dB 향상시켰다. 또한 제안한 시스템은 3차원 웨이브릿 변환을 이용하여 움직임 보상 에러의 전파를 제거하였고, 다분해능과 압축 비트율에 따라서 점진적 전송이 가능하다.

쿼드트리 알고리즘을 이용한 디지털 워터마킹의 성능 분석

강중순,추형석,Kang, Jung-Sun,Chu, Hyung-Suk 한국융합신호처리학회 2010 융합신호처리학회 논문지 (JISPS) Vol.11 No.1

본 논문에서는 쿼드트리 알고리즘을 이용한 디지털 워터마킹의 성능평가를 수행하였다. 제안한 알고리즘은 웨이블렛 영역에서 퀴드트리 알고리즘을 이용하여 워터마크의 중요계수를 선택하였고, Cox의 알고리즘을 이용하여 워터마크를 삽입하였다. 제안한 알고리즘의 성능 평가를 위한 시뮬레이션은 웨이블렛 영역에서 쿼드트리 알고리즘의 효과, DWT 변환 레벨과 대역(HH, LH, HL)에 따른 워터마킹 효과, 그리고 최저주파수 대역(LL)의 워터마킹 효과에 대하여 수행하였다. 시뮬레이션 결과에서 퀴드트리 알고리즘을 이용한 워터마킹은 고정된 대역의 중요계수에 워터마크를 삽입한 방법과 비교하여 향상된 결과를 보였고, 6 레벨 DWT에서 HH, HL LH 대역에 동시에 워터마크를 삽입하였을 경우에 가장 좋은 결과를 보였다. 또한, 전체 워터마크 중 30~60%를 LL 대역에 삽입하였을 경우에 PSNR 성능은 1~3dB 정도 떨어지나 추출한 워터마크의 상관도 값은 향상된 결과를 보였다. In this paper, digital watermarking method using quad-tree algorithm is proposed. The proposed algorithm searches the significant coefficient of the watermark by using quad-tree algorithm and inserts the watermark by the Cox's algorithm. The simulation for performance analysis of the proposed algorithm is implemented about the effect of quad-tree algorithm in wavelet domain and that of embedding watermark in each subband coefficient (HH, LH, HL) and each DWT level, and that of embedding in the lowest frequency band (LL). As a simulation result, digital watermarking using quad-tree algorithm improves the watermarking performance in comparison with inserting watermark in the significant coefficients of fixed frequency band. The watermarking performance of simultaneously embedding in HH, LH, and HL band of DWT(6 level) is better than that of different cases. In addition, insertion the watermark to the LL band about 30~60% of all watermarks improves the correlation value while PSNR performance decreases 1~3dB.